The present invention relates to novel prostaglandins of D series (referred to as prostaglandins D or PGDs hereafter), and tranquilizers and soporifics containing the compound.
Prostaglandin is a general name for prostanoic acids which is divided in E, F, A, B, C, D, H and the like according to the way keto or hydroxyl group introduced in five membered ring portions. In addition to stimulating uterine muscle, prostaglandins have various physiological and pharmacological activities such as vasodilation, inhibition of blood-platelet aggregation, anti-inflammatory effect and the like.
Prostaglandin D contains the following five membered ring: ##STR1## classifying roughly, PGD.sub.2 wherein C.sub.5 -C.sub.6 bond is double bond: ##STR2## and PGD.sub.3 wherein C.sub.17 -C.sub.18 bond is double bond; ##STR3## are known. For example, PGD.sub.2 is known to have activities such as analgesic activity, sedative activity, induction of sleep, thermoregulation and the like. However, activity which PGD.sub.2 may show greatly depends on the administration route thereof. For example, experiments using rats show that physiological sleep can not be induced by peripheral administration such as subcutaneous injection, intravenous injection, oral administration and the like but induced by administrating directly in the cerebral ventricle. Therefore, PGD.sub.2 is difficult to administrate. In addition, PGD.sub.2 also exhibits inhibition of blood-platelet aggregation, bronchoconstriction, constriction of enteron muscle, vasodilation and the like as well as side-effect such as severe diarrhea. Therefore, there exist problems to use PGD.sub.2 as tranquilizers and soporifics.
On the other hand, in metabolites of human or animal, the existence of analogues of prostaglandins D in the free form wherein carbons at 13 and 14 positions are saturated and that at 15 position forms carbonyl group is confirmed. These 13,14-dihydro-15-keto-prostaglandins D are ##STR4## and the corresponding PGD.sub.1 and PGD.sub.2 and, PGD.sub.3 are known as metabolites which are naturally produced in vivo by enzymatic metabolism. These 13,14-dihydro-15-keto-PGDs have been reported as physiologically and pharmacologically inert metabolites which barely exhibit various physiological activities that PGDs usually do (Accta Physiologica Scandinavica, 66, 509-(1966)).